I discovered that putting a USB drive into my Linux Mint PC resulted in it being read-only. After a little bit of googling I discovered a simple fix. It turned out that a minor corruption was the culprit.
First login as root:
$ sudo su -
<enter root password>
Find the drive with:
$ df -Th
In my case it was: /media/martin/735F-4AA5 and also note where it is mounted, in my case /dev/sdd1
So unmount it:
$ umount /media/martin/735F-4AA5
Find and fix any corruption:
$ dosfsck -a /dev/sdd1
Open the folder and look for a file starting with FSCK and ending with .REC.
Hint: It's likely called FSCK0000.REC
Now delete (move to trash) the file and then mount the drive and all should be good.
Simple :-)
